大气甲醛稳定碳同位素分析方法研究

利用气相色谱/燃烧/同位素比值质谱(GC/C/IRMS)技术,采用2,4-二硝基苯肼(DNPH)衍生化,初步研究了单体化合物稳定碳同位素方法研究大气甲醛来源问题.根据不同同位素组成的甲醛与DNPH反应,模拟大气采样,具体讨论了甲醛与DNPH衍生化过程的同位素效应及分析方法的重现性与精确度.结果表明,每个甲醛2,4-二硝基苯腙样品分析的最大标准偏差为0.3‰;不同同位素组成的甲醛衍生化产物甲醛2,4-二硝基苯腙与理论值的平均偏差为0.24‰±0.14‰(从0.03‰到0.35‰),小于仪器分析误差0.5‰,该衍生化过程不存在同位素分馏.采用该方法对酒店大厅内外大气甲醛碳同位素组成进行了初步研究,结果表明不同来源的甲醛同位素组成具有显著差异,可以为大气甲醛的来源分析提供非常有效的信息.

Stable Carbon Isotope Analysis Method for the Atmospheric Formaldehyde

A method of compound-specific stable carbon isotopic analysis for the research about the sources of atmospheric formaldehyde was preliminary studied using gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) via 2, 4-dinitrophenylhydrazine (DNPH) derivatization. In order to evaluate the reproducibility, the accuracy and the carbon isotope effects of the method, formaldehyde with different delta 13C values were used to simulate the sampling procedure. The results show that the maximal analytical deviation for all formaldehyde 2, 4-dinitrophenylhydrazone is 0.3 per thousand and the average deviations between the determined and theoretical delta 13C values of them are 0.24 per thousand +/- 0.14per thousand (ranged from 0.03 per thousand to 0.35 per thousand), less than 0.5 per thousand the technical specifications of the GC/C/IRMS system. These mean that no carbon isotopic fractionation occurred during the procedure. The study for the indoor and outdoor atmospheric formaldehyde in the restaurant show that the stable carbon isotopic compositions are significant different for different sources of formaldehyde. The present method could provide valuable information about the sources of atmospheric formaldehyde.